The present invention is directed to the continuous casting of metals, particularly in a steel mill operation.
By the year 1955 the continuous casting of steel, which in concept had been invented many years earlier, achieved a practical commercial form. This is evidenced by the article entitled "CONTINUOUS CASTING AT ATLAS STEELS, LTD.", by John F. Black and F. W. Rys, which appeared in the June, 1955 issue of IRON AND STEEL ENGINEER. An article entitled "CONTINUOUS CASTING OF STEEL" by Isaac Harter, Jr., was published in the April, 1956 issue of the same magazine. By 1964 at least sixteen other articles on this subject had been published in IRON AND STEEL ENGINEER.
Continuous casting produces a higher percentage yield of the metal than does the pouring of ingots. In terms of economics, the full advantage of continuous casting is achieved when the casting facilities are able to consume the entire contents of the melt furnace in a single cast.
It is inherent in the casting operation that initially it is only the outer surface of the metal which freezes into the cross-sectional configuration established by the mold. As the metal leaves the mold it consists of a thin exterior shell that is filled with a still molten interior. As the metal moves further away from the mold it must be progressively cooled until it is completely solidified. Mechanical support during the cooling process is a problem of some magnitude because, first, if the thin shell were to break open the molten metal in the interior would run out, and second, the static pressure of the molten interior portion of the metal continues to increase as it moves progressively further downward from the mold. Yet a further complicating factor is that excessive cooling will adversely affect the metallurgical characteristics of the resulting semi-finished metal.
It has been the accepted practice to employ guide rollers for guiding the casting along a desired pathway after it leaves the mold. The usual practice is to first guide the casting in a straight downward direction and then through a curved path of about 90 degrees until it arrives at a horizontal trajectory. Spray nozzles are positioned underneath the mold and are utilized to continuously spray water on the casting as it moves downward. The locations and design of the spray nozzles are carefully selected in order to achieve a desired cooling action. But the mechanical drive for withdrawing the casting from the mold is not accomplished either by the mold, by the guide rollers, or by the spray nozzles. This is left to another mechanism which is positioned many feet below the pouring ladle that initially furnished the molten metal to the mold, in the region where the horizontal trajectory has been reached. This mechanism conventionally takes the form of a number of pinch rollers which pull the casting horizontally away from the mold location.
One object of the invention is to provide a new and improved method for continuous casting of metal, particularly steel.
Another object of the invention is to provide an improved casting machine for the continuous casting of metals, which is far simpler and far less expensive than similar machines heretofore in use.
A further object of the invention is to provide novel specific mechanisms which may be advantageously used in continuous casting operations.